Safety switch



W. A. RAY

SAFETY swI'rcH June 1a, 1942.

Filed Sept. 26, 1941 a 9 2 O wm O 6 I 5 Mz k mv .15 w v i# O 5 w 2 wz 4 Z f Gttorneg Patented June 16, 1942 UNITED STATES PATENT GFFICE SAFETY SWITCH William A. Ray, Los Angeles, Calif.

Application September 26, 1941, Serial No. 412,379

(Cl. 20o-87) Claims.

My present invention relates to manually operable, electromagnetically controlled, switches of the type wherein manual means are provided for moving switching means into a controlling position, in which position they are maintained by electromagnetic means, the energization of which iscontrolled by means responsive to a condition such as temperature, pressure or the like. In the event that the degree of said condition attains an abnormal value, the electromagnetic means are deenergized, permitting the switching means to return to their unmoved positions.

It is an object of my invention to provide a switch of the type indicated having means for preventing actuation of the switching means by movement of the manual means unless the magnetic means are energized.

Another object is to provide a novel switch of the type indicated that is simple in construction, economical to' manufacture, and comprises but a single pair of normally independently movable elements.

In the prior art, the Vcurrent capacity of similar switches has been limited because of the necessity for exible connections to one or more of the movable contacts. Itis therefore another object of my invention to provide a switch of the type indicated, in which the necessity for ilexible leads is eliminated and is no longer a factor in determining the capacity of the switch.

Other objects and advantages of my invention will be found in the description, the drawing, and the appended claims.

For complete understanding of the invention, reference may be had to the following detailed description and accompanying drawing, wherein:

Figure 1 is a plan of a switch embodying my invention;

Figure 2 is a bottom view of the same;

Figure 3 is a longitudinal section taken along the line 3-3 of Fig. 1; and

Figure 4 is a transverse section taken along the line 4-4 of Fig. 1.

. In the drawing, the numeral II indicates a casing, preferably molded of insulating material such as Bakelite, having a thickened top wall or mounting base I2 in which are embedded the enlarged upper end portions I3 of two parallel-spaced downwardly-extending posts I4. In openings near the outer ends of two opposed arm portions I5 of a cross-shaped insulating disk I6, are bushings I1 which are riveted over at their lower ends to secure them to the disk. The bushings I1 are so spaced as to cooperate with the posts I4, Awhich provide free guiding means for the disk I6, the bushings being a loose fit on the posts. Compressed between the mounting base I2 and the disk I6 are springs I8 constantly urging the disk in a direction parallel with the posts and away from the mounting base. The lower end portions of the posts I4 are provided with annular grooves for lock washers I9 which limit the downward movement of the disk. I

Mounted on the disk I6 is an electromagnet having a U-shaped core 20, the upper end portions of the arms of which extend through openings in the disk I8 between the bushings I1. Around one of the arms of the core 20 is wound an energizing coil 2|, connected with terminals 22 by flexible leads 23. The core 20 is held in position, with the coil 2| clamped between it and the underside of the insulating disk I6, by a U-shaped metal band 24, the outwardly turned end portions 26 of which are secured to the disk by the riveted-over end portions of the bushings I1. Aw'idened portion 25 of the band 24 is bent over the sides of the core 20 to hold these two members in alignment.

Located on two other opposite end portions or arms 21 of the cross-shaped disk I6 are contacts 28, interconnected by a conductor 29. The contacts 28, extending through openings in the disk I6, are riveted over at their lower ends to hold them securely to the disk, and the interconnecting conductor is soldered to the riveted ends. I

Extending through an opening in the mounting base I2, centrally of the posts I4, is a rod 3l adapted for reciprocable motion parallel to the posts. The upper end portion 32 of the rod II is slightly enlarged, and D-shaped in cross section to conform to a similarly shaped opening in a metal band 33, which prevents rotation of the rod and also provides additional guiding means therefor.

A rod Jl, having a head 39 on its lower end, extends loosely through a centrally disposed opening in an armature 36, and into an axial opening in the rod ll where it is secured by means of a pin 34 extending through aligned transverse openings in the two rods. Encircling the rod SI, and compressed between the pin 34 and the upper side of the mounting base I2, is a spring constantlyurging the rod upward. I'he armature 36; rectangular in shape, and cooperable with the pole faces 31 of the electromagnet core 20, has a square-cut channelacross its contacting face to receive the rod head 39. which is iiatteneci on two sides to conform to the sides of the channel and'thus prevent rotation of the armature. The amature 85 is loosely mounted on the rod 38, and space is provided between the lower end of rod 3| and the upper side of the armature so that the armature is free to rock on the rounded portion of the head 39 adjacent the rod 38. The rockable mounting of the armature 38 on rod 38 will permit proper engagement of the pole faces 31 with the armature 36veven though the surface of one, or both, be initially in a tilted position. This is of considerable importance as the electromagnet is usually energized by very little power, such as that produced by a pilot-burner-heated thermoelectric generating device, and is not 'designed to attract the armature through space. By preventing rotation of the amature it is` possible to make it rectangular inshape, instead of the usual circular form, and of only slightly greater area than that of the pole-faces and the area ybetween them. Since the nickel-iron alloy, of which the armature is preferably constructed,

'is not only expensive, but also diilicult to obtain at this time, the saving in this material, effected by the present construction is ofy considerable importance. f

4Embedded in the mounting base |2, and yextending therethrough are metallic tubular members I6, in the llower ends of which are secured contact elements 40, adapted to be bridged Aby the interconnected contacts 28.l For-connecting the switch in an external circuit, terminal kscrews 4| are provided which arek connected to the upper portions of the members 46 by straps 42 lying in protective channels formed by the .raised portions 43, M rand 45 of the mounting base. Should one of the contacts 28 or l0 become of unequal length for any reason, such as due to unequal wear, tilting of the disk would be necessary in order that the contact elements 40 might be bridged. This eventuality is taken care of by the loose fit of the bushings on the posts H and by the rockable mounting'of the armature on the rod 3| which permit the Contact; elements to be'bridged although considerable tilting of the disk may be necessary. f f

lIn operation, if suflicient pressure is applied on rod 3| to overcome the force of spring 35, the armature 36 will be moved into' engagement with the pole faces 31 4of the electromagnet core 20, and spring 35 will becompressed. At this time, if the core is sufficiently energized, the electro# magnetic holding force will be greater thanthe force of spring 35, and pressurey on rod 3| may be released. The force of spring 35 being greater than the total force of springs i8, but less than that of `the electromagnetic holding force, causes the disk I6 to move toward the mounting` base until contacts 28 engage and bridge the contact elements I0. Engagement of the contacts 28 with contact elements 40 has prevented the rod and armature from fully 'returning to their'vormal positions, and consequently the spring 35 is still,

slightly compressed and is exerting a force tending tov separate the armature from the core. The contacts remain closed until the occurrence ofsome abnormal condition of means controlling l the energization of the electromagnet. rWhen this., condition arises, the electromagnet is deenergized and spring 35 pulls the armature away fromthe core. Theydisk assembly is moved to electromagnet must be energized and the resetting operation repeated.

Obviously, the respective positions of the electromagnet core 20 and its cooperating armature 36 could be reversed without changing the operation of the switch in any way. An important' invention, I wish it to be understood that modiiications may be made without departing from the spirit of my invention and that I intend, therefore, that my invention be limited vonly by the scope o f the appended claims.

I claim .as my invention: g y 1. In-a manually-operable electromagneticallycontrolled switch: a base member; apair of spaced contact elements insulatingly mounted in said base member and exposed atr one surface thereof; a member movable toward and away from said surface and biased in said last-named direction; s aid movable member comprising a conducting member cooperable with said contact elements to bridge the same when moved toward saidsurface; a manually operable rod extending through an opening through'said base member; andan electromagnet comprising a. core member and a cooperable armature member; one of said electromagnetmembers being mounted on the end of said rod adjacent said surfaceand the other on said movable member; Said rod being movable in one direction to a position in which the electromagnet members engage each other and are then magnetically retained in engagement while thecore element is energized, so that subsequent movement of the rod in an opposite direction is eiective to Inove'said movable member, against the force of said bias, to a position wherein said contact elementsare bridged by said conducting member.

2. Ina manually-operable electromagneticallycontrolled switch: a base memberbf insulating material; a pair of spaced contact elements in said base member and exposed at` onesurface thereof; a member movable toward and away from said surface; means biasing said movable member in said last-named direction; said movable member comprising a conducting member cooperabie with said contact elements 4to .bridge the same when said movable member is moved toward said surface; a manually operable rod extending through an opening through said base member.; and an electromagnetcomprising a core member and a cooperable armature member;`

one of said electromagnet members being mounted on saidvrod andthe other on said movable member; said core member having a Apole face directed toward said armature so that when the rod is moved in one direction the armature and pole face are brought into engagement, in which lengagement they are magnetically retained while the core member is energized, so thatsubsequent movement of therod in an opposite direction is eective to move said movable member, against theforce of said bias, to a position wherein said contact .elements are bridgedby said conducting member.

' said movable member in said last-named direction; said movable member comprising a conducting member cooperable with said contact elements to bridge the same when said movable member is moved toward said surface; a manually operable rod extending through an opening through said base member substantially centrally of said contact elements; an electromagnetic core member and cooperating armature member; one of said electromagnet members being mounted on said rod, the other being mounted on said movable member; said core member having a pole face directed toward said armature so that when the rod is moved in one direction the armature and pole face are brought into engagement, in which engagement they are magnetically retained while the core member is energized; and means urging the rod and electromagnet member thereon in an opposite direction; subsequent movement of the rod in said opposite direction being effective to move said movable member against the force of said bias to a position wherein said contact elements are bridged by said conducting member.

4. In a manually-operable electromagneticallycontrolled switch: a base member of insulating material; a pair of spaced contact elements molded in said base member and exposed at one surface thereof; an elongated member arranged substantially parallel to said surface and movable toward and away from the same; means biasing said movable member in said last-named direction; said movable member comprising a conducting member cooperable with said contact elements to bridge the same when said movable member is moved toward said surface; guide means for said movable member comprising a pair of spaced posts extending from said surface and cooperable with openings in opposite ends oi' the movable member; a manually operable rod extending through an opening through said base member substantially centrally of said con\ tact elements; an armature carried by the end of said rd adjacent said surface; an electromagnet mounted on said movable member and having a pole face directed toward said armature so that when the rod is moved in one direction the armature is brought into engagement with said pole face, in which engagement it is magnetically retained while the electromagnet is energized; and means urging the rod and armature in an opposite direction; subsequent movement of the rod in said opposite direction being effective to move said movable member, against the force of said bias, to a position wherein said contact elements are bridgedby said conducting member.

5. In a manually-operable electromagneticallycontrolled switch: a base member of insulating material; a pair of spaced contact elements molded in said base member and exposed at one surface thereof; an elongated member arranged substantially parallel to said surface and movable toward and away from the same; means biasing said movable member in said last-named direction; said movable member comprising a conducting member cooperable with said contact elements to bridge the same when said movable member is moved toward said surface; guide means fox' said movable member comprising a pair of spaced posts extending from said surface and cooperable with openings in opposite ends of the movable member; a manually operable rod extending through an opening through said base member substantially centrally of said contact elements; an armature carried by the end of said rod adjacent said surface; a U-shaped electromagnet core, the arms of which extend through openings in said movable member so that their pole faces are exposed on the side oi' the movable member adjacent said armature, so that. when the rod is moved in one direction the armature is brought into engagement with said pole faces and is magnetically retained in such engagement during the energization of said core; and means urging the rod and armature in an opposite direction; subsequent movement of the rod in said opposite direction being effective to move said movable member, against the force of said bias, to a position wherein said contact elements are bridged by said conducting member.

WILLIAM A. RAY. 

